1. Field of the Invention
The present invention relates to a battery pack.
2. Description of the Related Art
A secondary battery often has one unit battery (one bare cell) but may include a plurality of unit batteries in the form of a group battery to constitute a pack according to an external device to which it is applied.
In the latter case, a plurality of unit batteries are positioned in a case assembly, and the case assembly includes an upper case and a lower case.
Generally, the battery pack is formed by assembling the upper case and the lower case after positioning the unit batteries in the lower case.